Historically, seismic surveys utilized a source and a receiver on the surface of the earth. In these cases, the source and the receiver were considered to have only a horizontal offset. This made the geometry associated with processing the seismic data relatively simple. Seismic prospecting has evolved. Currently, many seismic prospecting methods use sources and receivers with both a horizontal and vertical offset. Examples of this are seismic profile data, vertical cable data, ocean bottom cable data and streamer data. This vertical offset causes the reflection of the raypath to be somewhere between the midpoint of the horizontal offset and the receiverxe2x80x94even for flat reflectors. Furthermore, the raypath is not symmetric about the reflection point.
For years seismic signal processing has concentrated on placing various traces in bins based on a common depth point (CDP) or common midpoint (CMP) for each trace. However, as stated above, with vertical offset data the reflection point is between the midpoint of the horizontal offset and the receiver. In order to continue to use CDP or CMP binning, the source and the receiver are vertically shifted to a flat datum to replicate the historic source and receiver positions. This is called a static shift. Then various traces are placed in bins based on a common depth point (CDP) or common midpoint (CMP) for each trace. This has inherent problems. By shifting the source and receiver the true reflector moves. This causes significant errors and the stacking image is smeared.
The current simple static vertical shift is inaccurate. Furthermore, common depth point (CDP) and common mid-point (CMP) binning does not produce quality results when utilized in situations with a vertical offset. There is a long felt need for a method which is more accurate than current techniques, but is equivalent in both expense and speed.
A method for processing three-dimensional seismic data is provided. The seismic data is at least partially the result of receiving a seismic wave with a seismic receiver. At least a portion of the seismic wave is generated by a seismic source. The source and receiver are both horizontally offset and vertically offset. The method comprises binning at least a portion of the seismic data in common reflection point bins. The method comprises sorting the seismic data within the bin to create common reflection point gathers. The method further comprises analyzing velocity, and applying surface consistent statics corrections to at least a portion of the seismic data within said common reflection point gathers. The method also comprises applying a non-hyperbolic normal moveout equation to at least a portion of said seismic data, and stacking at least a portion of said seismic data within said common reflection point gathers.
A system for processing three-dimensional seismic data is also provided. The system comprises means for binning at least a portion of the seismic data in common reflection point bins. The system further comprises means for sorting the seismic data within the bin to create common reflection point gathers. The system further comprises means for analyzing velocity and means for applying surface consistent statics corrections to at least a portion of the seismic data within said common reflection point gathers. The system also comprises means for applying a non-hyperbolic normal moveout equation to at least a portion of said seismic data, and means for stacking at least a portion of said seismic data within said common reflection point gathers.
An apparatus for processing three-dimensional seismic data is provided. The apparatus comprises a common reflection point binner, and a sorter. The apparatus further comprises a velocity analyzer. The apparatus further comprises a surface consistent statics corrector. The apparatus also comprises a non-hyperbolic normal moveout applicator, and a stacker.